We can tell you how great the Sahara retreat is but the photos and videos speak for themselves.
Check out the official video one of the yoga retreats:
The sun and moon paint the dunes with their shadows every day.
Click on the bottom right of the player to make it go fullscreen.
(Thanks to Sarah Markussen and Fabrice Knecht for these!)
And some more…
And Sahara images from the very first retreat in 2011!